COMPDH Process

What does it do?	How to access this process	Link to Command Table
Composites samples down or up drillholes.	Sample Analysis >> Prepare Samples >> Composite	Click here

Process Overview

Composites drillhole data down each drillhole. By use of retrieval criteria and a very large compositing interval, COMPDH can also composite over rocktypes or seams.

Compositing can be performed either down the hole from the collar, or up the hole from the EOH position.

The input file must be in standard sample format (as output by process DESURV). The output file is in an identical format. Up to a maximum of 20 explicit numeric data fields may be composited. These do not have to be specified; they are identified by the process as those fields which are not the standard ones (BHID, X, Y, Z, LENGTH, A0, B0, C0, RADIUS, FROM, TO).

Each drillhole is split exactly into fixed length composites for a length equal to the parameter @INTERVAL, starting normally from the collar; if the optional parameter @START is set, this is the distance down the drillhole at which compositing will begin.

If there is a gap between samples of less than or equal to a specified distance (parameter @MINGAP) it will be ignored; that is, the missing part will be assigned the grades of the whole composite. Any gap greater than this, but less than or equal to the parameter @MAXGAP, will be replaced by a dummy sample with the default values specified in the file. A gap larger than @MAXGAP will be taken to terminate the composite.

If the total length of samples with non-absent grade values within a composite is greater than @MINCOMP, then the average grade of those samples is assigned to that grade field for the entire composite. If the total length of samples with non-absent grade values within a composite is less than @MINCOMP, then that grade field is assigned an absent data value for the entire composite. For example:

 

If @MINCOMP=0.1, this is less than the assayed length of 0.39 and so the grade of 15.2 is assigned to the whole composite. If @MINCOMP=0.5, this is greater than the assayed length of 0.39 and so the absent data grade of - is assigned to the whole composite.

The file must be in the order of BHID and FROM, i.e. sorted in drillhole order in increasing downhole distance. This is the order output from the DESURV process.

Weighting by density

If a density field exists in the file then this may be used to for density weighted compositing. The density field is defined as the optional field *DENSITY. If any density value is absent data then the default density value will be used.

Weighting by core loss or recovery

To take into account the effects of core loss, the user may specify one of two optional fields *CORELOSS (core loss as a percentage) or *COREREC (core recovery as a percentage) to be used during compositing. The lost portion of the core will be taken into account and used in compositing. The actual treatment depends on the optional @LOSS parameter.

If @LOSS<=0 (default) then the lost part of the core will be assumed to have exactly the same grades, properties etc. as the recovered part. Core loss is ignored.

If @LOSS=1 then the lost core will be assumed to have default grades, density, properties etc. which will be averaged with the recovered core values. Note: This requires that the drillhole file has default values for density & any other fields that need to be calculated.

If @LOSS>=2 then the lost core will be treated as cavity (zero density and grades) so that the grade of the total sample is effectively reduced by the cavity.

Adjusting the composite interval

The parameter @MODE can be used to force equal composite lengths. If @MODE=0 (default) then part or all of one or more samples may be excluded from a composite. Setting @MODE=1 forces all samples to be included in one of the composites by adjusting the composite length.

For example if the sample data file contains 10 1m composites, and @INTERVAL=3 and the default @MINCOMP value of 1.5m is selected, then the output file will contain 3 3m composites. The final 1m sample will not be included in any composite. However if @MODE=1, then 3 composites each of length 3.333m will be created. If there were only 8 1m samples in the sample data file, then 3 composites of length 2.667m would be created.

Input Files

Name	I/O Status	Required	Type	Description
IN	Input	Yes	Drillhole	Sample data file, sorted on BHID and FROM. Expects fields BHID, FROM, TO, LENGTH, X, Y, Z, A0, B0.

Output Files

Name	I/O Status	Required	Type	Description
OUT	Output	Yes	Drillhole	Composite file.

Fields

Name	Description	Source	Required	Type	Default
BHID	Drillhole identifier.	IN	No	Any	BHID
FROM	Downhole distance to sample top.	IN	No	Numeric	FROM
TO	Downhole distance to sample bottom.	IN	No	Numeric	TO
DENSITY	If present, composites will be density- weighted.	IN	No	Numeric	DENSITY
CORELOSS	If present, will be taken as percentage core loss, and treated according to the LOSS parameter.	IN	No	Numeric	CORELOSS
COREREC	If present, will be taken as percentage core recovery, (100-core loss) and treated according to the LOSS parameter.	IN	No	Numeric	COREREC
ZONE	Name of first field for compositing within. (may be numeric or up to 32 character alpha). This field must exist in the IN and will be copied to the OUT file. If specified then new composites will be created each time the value of ZONE changes.	IN	No	Any	Undefined
ZONE2	Name of second field for compositing within. (may be numeric or up to 32 character alpha). This field must exist in the IN and will be copied to the OUT file. If specified then new composites will be created each time the value of ZONE changes.	IN	No	Any	Undefined
ZONE3	Name of third field for compositing within. (may be numeric or up to 32 character alpha). This field must exist in the IN and will be copied to the OUT file. If specified then new composites will be created each time the value of ZONE changes.	IN	No	Any	Undefined

Parameters

Name	Description	Required	Default	Range	Values
INTERVAL	Composite length.	Yes	Undefined	Undefined	Undefined
MINGAP	Gap length to be ignored. The default gap is calculated as 0.05 INTERVAL. This default value is applied if the parameter is not specified, or if the value is specified as <=0. A gap of exactly zero is not permitted. If you want the composite to be split at every gap, use a very small value for MAXGAP eg 0.0001.	No	Undefined	Undefined	Undefined
MAXGAP	Gap length for termination of composite (0).	No	0	Undefined	Undefined
MINCOMP	Minimum composite length [0.5 INTERVAL].	No	Undefined	Undefined	Undefined
LOSS	If core loss or core recovery field is present, controls how it is handled: <=0 treat loss as part of sample =1 treat loss as default values >=2 treat as cavity [zero density and grades]	No	Undefined	Undefined	Undefined
START	Starting distance down hole (0).	No	0	Undefined	Undefined
MODE	If MODE is 0, the default, then the maximum composite length will be defined by the INTERVAL parameter and the minimum composite length by the MINCOMP parameter. Thus it is possible for part or all of one or more samples to be excluded from the composite. Setting MODE to 1 forces all samples to be included in one of the composites by adjusting the composite length, while keeping it as close as possible to INTERVAL. The maximum possible composite length will then be 1.5*INTERVAL. (0)	No	0	0,1	0,1
DENSITY	Default density value of samples. This is used if no DENSITY field exists or if the DENSITY field contains absent values. If this is unset then the default DESNITY in the input file data definition is used as the default.	No	Undefined	Undefined	Undefined
REVERSE	Reverse compositing direction. Control whether compositing is done from collar to toe (default) or toe to collar. 0 : Composite samples starting at the collar. This is the default. 1 : Composite samples from the toe to the collar.	No	0	0,1	0,1
PRINT	=3 to display each composite and output file DD (0).	No	0	0,3	0,1,2,3

Notes

A progress message is displayed every 500 samples read.

Example

!COMPDH

&IN(.D), &OUT(COMPS.4), @INTERVAL=4

>>> 170 SAMPLES INPUT <<<
>>> 67 COMPOSITES OUTPUT <<<

!COMPDH

&IN(BHOLES.D), &OUT(SEAM.1), @INTERVAL=999999, @MINCOMP= 1, SEAM= 1

>>> 345 SAMPLES INPUT <<<
>>> 42 COMPOSITES OUTPUT <<<

Here the interval is set very large to force compositing over the entire seam, selected as the value of field "SEAM"=1 in the input file. The minimum composite length is set to 1, the minimum mining width.

Error and Warning Messages

Message	Description	Solution
>>> ERR 122 <<< ( fileno) IN COMPDH	Missing essential fields in input sample file or there are more than 20 explicit numeric data fields for compositing. Fatal; the process is exited.
>>> ERR 124 <<< ( fileno) IN COMPDH	The composite length specified in @INTERVAL is negative or zero. Fatal; the process is exited.